Salah, who earlier was on target to put the Reds 2-1 ahead before Newcastle levelled, was left needing medical attention midway through the second half after being floored following a collision with goalkeeper Martin Dubravka.
The Slovakian shot-stopper appeared to accidentally strike Salah with his hip as he rose to punch the ball away from danger. Salah was unable to continue and was carried off the pitch and down the tunnel at St James' Park.
Divock Origi came off the bench to replace Salah and dramatically scored the winner as Liverpool clinched a 3-2 victory that puts them back ahead of Manchester City in the Premier League title race.
Jurgen Klopp's Liverpool will next hope to overturn a three-goal deficit when they face Barcelona in the Champions League semi-final second leg on Tuesday before their final game of the league season at home to Wolves.
It remains to be seen what part – if any – Salah will play in those two games.
Egypt international Salah's goal was his 100th league strike in European top-flight football, with 56 of those coming in the Premier League.
